Test of ablation
heatshield. The nose-cone capsule for Big Joe had no retrorocket package.
The inner structure held only a half-sized instrumented pressure vessel instead of a pressurized
cabin contoured to the outer configuration. Built in two segments, the lower half by Lewis and
the upper by Langley, the main body of the spacecraft replica was fabricated with thin sheets
of corrugated Inconel alloy in monocoque construction. This model of the Mercury capsule had
more than one hundred thermocouples around the capsule skin to register temperatures inside
and under the heatshield, sides and afterbody. (Reference NASA SP-4201 p. 201)

The Atlas 10-D was programmed to rise, pitch over horizontally to the Atlantic before it
reached its 100-mile peak altitude, then pitch down slightly before releasing its corrugated nose
cone at a shallow angle barely below the horizontal.

The original launch date for Big Joe was July 4, 1959 but the launch date was postponed until
min-August by the Air Force because the booster did not checkout out perfectly at first. Then
it was put off until early September by Space Task Group (STG) engineers, who were working
on instrumentation and telemetry problems. Finally, the count picked up on 9/8/59 when Atlas
10-D (the sixth of this model to be flight tested) stood on the launch pad with a Mercury
capsule (minus its escape tower).

About 2:30am a 19-minute hold in the countdown was called to investigate a peculiar indication
from the Burroughs computer that was to guide the launch. A malfunction was found in the
Azusa impact prediction beacon, a transponder in the booster. Since there were several
redundant means for predicting the impact point, the trouble was ignored and the countdown
resumed. Liftoff occurred at 3:19am. EST.

Landing:

About 7 hours after launch, the destroyer Strong reported that she had netted the boilerplate
capsule intact.

Mission Highlights:

Spacecraft test successful, Launch Vehicle Failure. The two outboard engines had not
separated from the centerline sustainer engine after their fuel was exhausted. The added
weight of the booster engines retarded velocity by 3000 ft per second and the capsule
separated from the booster 138 seconds too late. T he impact point was 500 miles short.